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New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.1/33

Suggested answers to Practical Workbook for SBACh 7 Gas exchange in humansPractical 7.1Questions (p. 7-2)1 A Nose C Epiglottis E Cartilage G Right lung I 2 Intercostal muscle B Pharynx D Trachea F Right bronchus H Rib J Diaphragm

Examination of the mammalian breathing system

Nostrilsnasal cavitypharynxlarynx tracheabronchibronchioles air sacs(in lungs)

3 4 5

The air is moistened, warmed and cleaner. It closes the entrance to the larynx during swallowing, thereby preventing choking. It protects the lungs and the heart.

Practical 7.2Results (p. 7-5)1 2 3 4

Examination of the pig lungs

There are three lobes in the left lung and two lobes in the right lung. The trachea is hard. The lung tissue is soft and spongy. The lungs increase in volume. / The lungs expand. The piece of lung tissue floats in water.

Oxford University Press 2009

New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.2/33

Oxford University Press 2009

New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.3/33

5

Questions (p. 7-5)1 2 3 4 It is because they have a very rich supply of blood vessels. The trachea, but not the lung tissue, is supported by cartilages. Air. The lungs tissue floats in water because the air in the air sacs gives the lung tissue a low density.

Oxford University Press 2009

New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.4/33

Practical 7.3Results (p. 7-8)

Examination of the mammalian air sacs

Questions (p. 7-8)1 In the air sacs, the oxygen concentration is higher than that in the capillaries. Oxygen in incoming air dissolves in the water film lining the air sacs, and then diffuses across the walls of the air sacs and the capillaries into the blood. In the capillaries, the carbon dioxide concentration is higher than that in the air sacs. Carbon dioxide in blood diffuses across the walls of the capillaries and the air sacs into the air in the air sacs. The large number of air sacs provides a large surface area for gas exchange. The epithelium of the air sac is only one-cell thick. This provides a short distance for rapid diffusion of gases. The moist inner surface allows gases to dissolve in the water film for diffusion across the epithelium. The air sacs are richly supplied with blood. This allows rapid transport of gases to and from the air sacs so that a steep concentration gradient can be maintained for rapid diffusion.

2

Practical 7.4

Comparison of the composition of inhaled air and exhaled air

Results (p. 7-11)Inhaled air Burning time of candle(s) Final colour of hydrogencarbonate indicator 14 Red / orange Exhaled air 10 Yellow

Oxford University Press 2009

New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.5/33

Oxford University Press 2009

New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.6/33

Questions (p. 7-11)1 The exhaled air contains less oxygen than inhaled air. The candle in exhaled air burns shorter. Some oxygen in the inhaled air diffuses from the air sacs into the capillaries. Therefore, less oxygen is found in the exhaled air. The exhaled air contains more carbon dioxide than inhaled air. The colour of hydrogencarbonate indicator turns yellow. Some carbon dioxide diffuses from the capillaries to the air sacs. Therefore, more carbon dioxide is found in the exhaled air. Lime water. The colour of lime water changes from colourless to milky.

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Conclusion (p. 7-12)The exhaled air contains less oxygen but more carbon dioxide than inhaled air.

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New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.7/33

Ch 8 Transport in humansPractical 8.1Results (p. 8-2)1

Examination of a blood smear

2 Red blood cell Shape Nucleus Relative size Relative number Biconcave disc shape No nucleus Medium Abundant White blood cell Irregular shape Round or lobed Large Rare Blood platelet Irregular shape No nucleus Small Occasional

Questions (p. 8-2)1 a b 2 a White blood cell is the largest. Blood platelet is the smallest. Red blood cell is the most abundant. White blood cell is the least abundant. It is biconcave disc shape. This provides a large surface area to volume ratio to facilitate the diffusion of gases.

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New Senior Secondary Mastering Biology Practical workbook answer

Book 1B p.8/33

b

No. The absence of nucleus allows the accommodation of more haemoglobin.This increases the oxygen-carrying capacity of the red blood cells.

3

The body is infected with pathogens. The body has abnormal cell growth.

Practical 8.2

Examination of the transverse sections of an artery and a vein

Results (p. 8-4)1

2 Artery Thickness of wall Size of lumen Thicker Smaller Vein Thinner Larger

Questions (p. 8-5)1 Arteries have a thicker wall which contains a thick layer of muscles. The muscles contract and relax to regulate the blood flow to body cells. Veins have a larger lumen to reduce resistance to blood flow. There are valves in veins but not in arteries (except in pulmonary artery and aorta).

2

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Practical 8.3Results (p. 8-7)1

Examination of the capillary flow in a fish tail fin

Observations Direction of blood flow Speed of blood flow Diameter of blood vessels Behaviour of blood cells One way Slow Similar to the diameter of red blood cells The red blood cells are squeezing their way through the capillaries.

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Questions (p. 8-8)1 To provide a large surface area for rapid exchange of materials between the blood and the body cells. To provide a large total cross-sectional area so that blood flows slowly in the capillaries. This allows a longer period of time for exchange of materials. 2 White blood cells can change their shape, so they can move along the narrower capillaries.

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Practical 8.4Results (p. 8-12)1

Dissection and examination of a pig heart

2 Water run into venae cavae pulmonary artery pulmonary vein aorta What happens Water comes out from the pulmonary arteries. Water cannot enter and no water comes out from any vessels. Water comes out from the aorta. Water cannot enter and no water comes out from any vessels.

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3 A Anterior vena cava B Right atrium C Posterior vena cava D Tricuspid valve E Right ventricle F Septum G Pulmonary artery H Aorta I J Pulmonary vein Semilunar valve

K Left atrium L Bicuspid M Heart tendon N Left ventricle

Questions (p. 8-13)1 When water is forced through the venae cavae and the pulmonary vein into the heart, it enters the heart and comes out as in the normal circulation. However, when water is forced through the pulmonary artery and the aorta, it cannot enter the heart because it is stopped by the semilunar valves. The wall of the left ventricle is thicker than that of the right ventricle. It is because the left ventricle has to provide a greater force to pump blood to all parts of the body (except the lungs), whereas the right ventricle pumps blood only for a short distance to the lungs. The ventricles have a thicker muscular wall. It is because the ventricles have to provide a greater force to pump blood to the lungs or other parts of the body, whereas the atria only pump blood to the nearby ventricles. 1 2 The ventricles have a thicker muscular wall to pump blood to all parts of the body. Valves are present to prevent backflow of blood.

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3 Heart tendons are present to prevent the valves from being turned inside-out when the ventricles contract. 5 The septum prevents the oxygenated and deoxygenated blood from mixing. This ensures a high oxygen content in the blood in the aorta for the body cells.

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Ch 9 Nutrition and gas exchange in plantsPractical 9.1 Investigation of the effects of different minerals on plant growthResults (p. 9-3)1 2 Flask A B C D E Appearance of seedlings Healthy growth of seedlings. Poor growth. Yellowing of older leaves. Poor growth. Depending on the species, leaves may become dull green, yellow or purple. Poor growth. Older leaves start to yellow at the edges, and then turn brown. Leaves may curl and dead spots appear. Poor growth. Yellowing of older leaves. (Answer varies with seedlings.)

Questions (p. 9-4)1 This prevents algal growth in the solutions. Algae take up the minerals in the solutions and affect the results. It ensures the roots get enough oxygen for respiration. Respiration can provide energy for the root to absorb minerals by active transport. All the major elements (e.g. nitrogen, phosphorus, potassium, magnesium, etc.) and trace elements (e.g. manganese, copper, zinc, etc.) needed by the plants. It acts as a control to show that symptoms appear in the seedlings are due to the deficiency of a particular mineral. Seedlings cannot use atmospheric nitrogen directly. Seedlings obtain nitrogen only in

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